This application is related to commonly-assigned U.S. patent application Ser. No. 12/331,824, filed Dec. 10, 2008.
The present invention relates generally to the operation of a generator associated with a turbomachine, and more particularly, to a method of reducing the time to synchronize the generator to an electrical grid system (hereinafter “grid”).
“Fast Start” and “Rapid Response” may be considered operating modes that require a turbomachine to export a load to a grid within a certain time after an operator initiates a start of that turbomachine. Fluctuating energy demand is a major factor in determining when the turbomachine operates. Turbomachines are commonly idled until sufficient demand requires operation. When demand requires operation, the turbomachinc performs a start-up process before exporting the desired electricity.
Generally, a synchronization process requires that three parameters of the generator be within an acceptable range of the corresponding three parameters of the grid. These parameters are: voltage, speed/frequency, and phase angle. The aforementioned parameters are commonly not a consideration until the turbomachine reaches full-speed-no-load (FSNL). Here, the phase angle is an uncontrolled variable during the sync process. This leads to a wide variation in the time required to synchronize. In addition, an undesired transient may occur when the breaker is closed due to the continued acceleration of the turbomachine. During the start-up process the turbomachine follows a particular acceleration schedule, which is generally dependent on physical parameters, such as, but not limiting of, thermal transients, exhaust temperature, airflow, etc.
There are a few issues with the current synchronization process. In some applications, such as, but not limiting of, Fast Start or Rapid Response, variations in synchronization process time may be unacceptable. This may prevent the powerplant from meeting operational requirements.
Therefore, there is a desire for an improved synchronization process. The improved process should reduce the power transient currently experienced during the synchronization process. The method should also reduce the variations in synchronization process times when the turbomachine is operating in a Normal Mode or a Fast Start Mode. This method should also provide a more consistent and repeatable synchronization process.